The Real Meaning of the 10% Rule

I wrote this article as a guest post on the Marathon Nation blog. It is reprinted (with slight modifications) here by permission.

People realized years ago that runners might try to do more in their training than their bodies could handle, that is, they might do too much too soon. Over time, suggestions about increasing distance and speed were formalized into the 10% rule. This rule became one of the foundation-stones of recreational running. However, some people have misunderstood the rule and have tried to follow it in ways that were probably not intended.

Let’s take a look at the 10% rule to determine if it is (or isn’t) a good rule for us to follow. The versions of the rule that I have read state that increases in distance or speed shouldn’t exceed 10% of the weekly amount. Nothing is said about gender, age, or goals in running. The rule lumps everyone together and gives an upper cap on the amount of increases in ones training. Running, jogging, or walking puts stress on our bodies, so when we talk about increases in distance or speed, we’re talking about increases in stress.

Many runners have believed they are exceptions to the 10% rule, and they have ignored the rule with no apparent harm to their bodies.  Other runners have considered the rule as an absolute pillar of their training, and they believe that 10% should be the size of the increases, not just a cap on the increases. Some runners have done this with success. Other runners, though, have learned that 10% increases are more than their body can handle, while still others have learned that 10% increases are too small for their needs.  So, it seems that increases of 10%  are not a cardinal rule of running without injury.

The 10% rule was discussed in an article in The New York Times. The Times reported on a scientific test to determine if 10% increases did decrease injuries. The runners were novice runners. Half of them followed an 11-week training program that specified 10% increases, and half of them followed an 8-week program with a more rigorous schedule having larger increases. The runners in both groups ran three times per week, and they reached their goal of doing approximately 90 minutes per run. Did the runners making 10% increases have fewer injuries? Nope! Those runners took three weeks longer to reach their goal, and they had as many injuries as the runners in the other group.

It seems we need to replace the 10% rule with more realistic suggestions, keeping in mind that we need rest between our runs.

• Listen to your body to learn how much increase in stress your body can handle.
• Keep your training within the bounds of stress that your body can handle.
• Realize that the limits on stress that apply to your body are likely different than the limits needed by others.
• After each increase in distance or speed, stay at the new level as long as it takes for your body to adjust to the new stress.
• Understand that as you get older, your body may be injured by stress that would have been compatible with your body when you were younger.
• Realize that if your body encounters too much stress, injury may occur, but it may take weeks or months for your body to become injured.

These suggestions put the responsibility on each runner to determine how much increase in distance or speed should be made and how often such increases should occur. They are general suggestions that can be used by men and women of any age.